Dear everyone, I encountered a problem when conducting ISAM simulation using CMAQ v5.5. I would thank you for helping to solve this problem. The specific process is as follows: I extracted the source apportionment results of PM2.5 components for January and February 2024, but the results showed that dust contributed a very high amount to nitrate. I can’t understand why? The specific details are as follows.
When you speciate PM emissions from the “Fugitive Dust (Non-Combustion)” sector, are you assigning any of these emissions to primary nitrate? If PM emissions from that sector are large and/or you are assigning a substantial fraction of these emissions to primary nitrate, that contribution may not be negligible relative to the (mostly secondary) nitrate from the other sectors you are tracking in ISAM.
Yes, I checked the emission of dust. The proportion of PNO3 in the dust sources is about 7% of the total dust sources, and then the proportion of PNO3 in the dust sources to all PNO3 sources is about 18%. In the cities I analyzed, the proportion of dust in the urban NO3 source apporation results is 10-16%. Currently, this result is very strange because nitrates are mainly secondary. The proportion of dust in nitrate should be much lower than that of PNO3